RECONSTRUCTION OF SQUEEZING BY A 3-LEVEL QUANTUM FILTER

It is shown that a three-level system with suitable values of electrom agnetic coupling between the levels is capable of absorbing the photon of a one-photon state in a squeezed mode but not one of the photons o f the two-photon state in this same mode, allowing reconstruction of t he squeezing of a previously squeezed state degradated by losses. Also a dissipative version is proposed in which the intermediate level is coupled to a continuum which dumps out the oscillation due to the filt er precessions.